Tuesday means: The third day of the week in many religious traditions, and the second day of the week in systems that use the ISO 8601 norm; it follows Monday and precedes Wednesday.. There is no real cause for parental concern; it is descriptive vocabulary rather than risky behaviour. If your teen uses it, context will usually make the intent clear. A short, curious question about where they heard it is usually all that is needed to know whether to follow up.